Recycling Plastic Marine Litter

[Pages:36]Recycling Plastic Marine Litter

N O W P A P

Northwest Pacific Action Plan

October 2007

Prepared in 2007 by the Special Monitoring and Coastal Environmental Assessment Regional Activity Centre

of the Northwest Pacific Action Plan (NOWPAP CEARAC)

Established at the Northwest Pacific Region Environmental Cooperation Center (NPEC) 5-5 Tower111 6th floor, Ushijimashin-machi, Toyama City, Toyama 930-0856 JAPAN TEL: +81-76-445-1571 FAX: +81-76-445-1581 Website: E-mail: webmaster@cearac.

Acknowledgments

This booklet was prepared by NOWPAP CEARAC within the framework of the Marine Litter Activity (MALITA) project, which was approved by the 10th NOWPAP Intergovernmental Meeting in November 2005. This booklet is based on "Research Report of Marine Litter Recyclability 2007" published by NPEC in 2007, which is supported by the Nippon Foundation.

For bibliographical purpose, this document may be cited as: NOWPAP CEARAC 2007: Recycling Plastic Marine Litter.

TABLE OF CONTENTS

1. Introduction ...................................................................................... 1 2. Basic knowledge of plastics ............................................................. 2

2.1 Production process of plastics .................................................. 2 2.2 Types and characteristics of plastics ......................................... 3 3. Plastic recycling technologies .......................................................... 5 3.1 Material recycling....................................................................... 7 3.2 Chemical recycling................................................................... 13 3.3 Thermal recycling..................................................................... 27 4. Issues and suggestions on recycling plastic marine litter.............. 32

1. Introduction

Marine litter is a serious global problem, and is known to have significant environmental, economic, health and aesthetic impacts. In many cases, plastics are one of the most abundant components of marine litter, mainly due to its very slow rate of degradation and ever-increasing uses in our society. Figure 1 summarizes the findings of the marine litter survey conducted along the Japanese coast of the NOWPAP region in 2004.

Cloth 0.2%

Paper 0.3%

Expanded polystyrene

18.0%

Glass/ceramic 2.8%

Metal 0.6%

Other 1.0%

Rubber 0.3%

Plastics 76.8%

Figure 1 Composition of marine litter along the coast of Japan in 2004

Source: NPEC (2006); Report on the marine litter survey of the NOWPAP coastal area in 2004

The figure shows that almost 80% of the marine litter found was comprised of plastic products, and if we include expanded polystyrene, the proportion of plastic products would be almost 95%.

Although various countermeasures are now being implemented to remove plastic litter from the sea coast, such as beach clean-up activities, installation of marine litter containment booms and so on, significant problems still persist in treating/disposing of the collected litter. Common approaches include landfill and incineration, but these methods are not always ideal solutions due to limited landfill space and pollution risks.

One possible solution to the treatment of plastic marine litter is to apply the technologies of plastic recycling, which is now commonly employed to treat industrial and domestic waste plastics. For example, marine waste plastics can be recycled into plastic

raw material, fuel oil, chemical feedstock and other products (see Chapter 3). This booklet has been prepared, in recognition of the benefits of plastic waste recycling,

to introduce the existing and developing plastic recycling technologies with the potential application for managing plastic marine litter. The booklet also describes some issues involved in recycling plastic marine litter, with some suggestions (see Chapter 4).

2. Basic knowledge of plastics

2.1 Production process of plastics Although many types of plastic are currently manufactured for a variety of purposes, the

raw material of these plastics is mainly derived from petroleum products, such as naphtha, which are extracted from crude-oil distillation.

When naphtha is thermally decomposed, simple molecules (monomers) such as ethylene, propylene, butane/butylenes and aromatics can be extracted. The raw materials of plastics are made when these monomers are chemically bonded into larger molecules called polymers (polymerization). Different types of plastics can be made by altering the combination of these monomers. Figure 2 shows an example of polymerization of ethylene into polyethylene.

Figure 2 Polymerization of ethylene into polyethylene Since these polymers are in powder or lump form, they are usually processed into pellets for easier handling. The final plastic product is then manufactured by processing (e.g. molding) the plastic pellets into various shapes and forms.

2.2 Types and characteristics of plastics

Plastics can be broadly classified into two groups: thermoplastics and thermosetting plastics. Thermoplastics can be repeatedly softened by heating and hardened by cooling, like candle wax. For this reason, thermoplastics can be remolded and reused almost indefinitely. Many types of thermoplastic products are manufactured to suit a wide range of purposes, such as for packaging, food containers and household products. More heat-resistant and durable thermoplastics are used in machines, automobiles and electrical goods.

Conversely, thermosetting plastics harden permanently after being heated. They are mainly used for products that require high heat resistance, because these plastics can be heated to high temperatures without melting. Table 1 shows some of the common thermoplastics and thermosetting plastics, and their main uses.

Table 1 Thermoplastics and thermosetting plastics and their main uses

Plastic type

Abbreviation

Main uses

Polyethylene

PE

Packaging, agricultural film,

construction sheeting

Polypropylene

PP

Bathroom products, packing string

Polystyrene

PS

Office appliances, CD cases

Expanded polystyrene

EPS

Fish boxes, food trays, packaging

Acrylonitrile-styrene (AS)

SAN

Tableware, lighters

resin

Acrylonitrile butadiene

ABS

Travel trunks, furniture, automobiles

Thermoplastics

styrene (ABS) resin

Polyvinyl chloride

PVC

Water pipes, hoses, agricultural film

Polyvinylidene chloride

PVDC

Cling film, ham casing, artificial turf

Methacrylic resin

PMMA

Headlight lenses, windshields, contact

lens

Methacrylic styrene resin

MS

Lenses, light covers, packaging

Polymethylpentene

PMP

Microwave tableware, film packaging

Polyamide (nylon)

PA

Fasteners, cogs, automobile parts

Polycarbonate

PC

Lunch boxes, CDs, driers, bottles

Acetal resin

POM

Fasteners, automobile parts

Polyethylene terephthalate

PET

PET bottles, VTR tapes, egg boxes

Phenol resin

PF

Printed circuit boards, pan handles

Thermosetting plastics

Melamine resin

MF

Tableware, laminates, paint

Urea resin

UF

Buttons, caps, electrical products

Unsaturated polyester

UP

Bathtubs, helmets, fishing rods

resin

Epoxy resin

EP

Electrical products, paints, adhesives

Polyurethane

PUR

Cushions, mattresses, heat insulation

Source: Plastic Waste Management Institute (2004); An Introduction to Plastic Recycling

3. Plastic recycling technologies

Plastic recycling technologies can be typically classified into three methods: material recycling (or mechanical recycling), chemical recycling (or feedstock recycling) and thermal recycling (or energy recovery)1. General descriptions of the three recycling methods are provided in the following sections, and specific examples of each are given. Table 2 shows the recycling examples introduced in this Booklet.

Table 2 Types of recycling examples introduced in the Booklet

No.

Recycling products

Recycled products

Material recycling

1 Industrial PE and PP waste plastics

Plastic pellets (used to produce other

plastic products)

2 Waste fishing nets

Plastic pellets

3 Waste EPS floats

Polystyrene ingots (used to produce

other plastic products)

4 Waste ABS floats

New ABS floats

Chemical recycling

5 Waste EPS products

Polystyrene pellets (new EPS products)

6 Waste PE and PP products

Aromatics (raw material for chemical

and medical products) and lower olefin

(raw material of plastics)

7 Waste polyester products

Dimethyl terephthalate and ethylene

glycol (raw material for plastics)

8 Tolylene diisocyanate (TDI) residues Toluenediamine (raw material for TDI)

(TDI: raw material of polyurethane)

9 Domestic waste plastics

Fuel oil

10 Waste PE, PP, PS plastics

Fuel oil

11 Low-grade oil produced from waste High-grade oil

plastic recycling

12 Domestic and industrial waste plastics Reducing agent of blast furnaces

13 Waste vinyl chloride products

Hydrocarbons (reducing agents for blast

furnaces), hydrogen chloride (used by

1 These terms (material recycling, chemical recycling and thermal recycling) will be used in this booklet, although other terms might be used elsewhere.

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